JPH0768388B2 - Antistatic polyester film - Google Patents

Description

The present invention relates to a polyester film having excellent antistatic properties.

[Problems to be Solved by Conventional Techniques and Inventions]

The biaxially stretched polyester film is widely used because of its excellent properties, but it has a drawback that it is easily charged.

Examples of the antistatic method include a method of kneading an anionic compound such as an organic sulfonate or an organic phosphate, a method of depositing a metal compound, a method of applying an anionic compound or a cationic compound or so-called conductive particles, and the like. is there.
Although the method of kneading an anionic compound can be manufactured at low cost, it has a limit in the antistatic effect and the compound that can be used is a low molecular compound, so that the adhesion between the film and the laminated layer is deteriorated by blooming. However, there are problems such as lack of water resistance and transfer of the compound. The method of vapor-depositing a metal compound has excellent antistatic properties, and although its application is expanding as a transparent conductive film in recent years, it is high in manufacturing cost and suitable for specific applications, but as a general antistatic film. Is hard to use. The method of applying conductive carbon or conductive metal particles has an advantage that the antistatic effect is relatively good and can be manufactured at a relatively low cost, but has a drawback that the transparency of the film is deteriorated.

For this reason, the method of applying an anionic compound or a cationic compound as an antistatic agent is widely used as an antistatic method for biaxially stretched polyester. As a method for producing a biaxially stretched polyester film having a coating layer,
There is a so-called coating stretching method (in-line coating method) in which a film is stretched and heat treated after coating with a coating liquid.
Compared with the method of forming a coating layer by coating the coating liquid on the polyester film after biaxial stretching, this method performs film formation and coating at the same time, so a wide product can be obtained at a relatively low cost. In addition, the adhesiveness between the coating layer and the polyester film of the substrate is good, and not only the coating layer can be made thin, but also the surface characteristics of the coating layer are characteristic.

However, when an antistatic polyester film is produced by coating stretching, the antistatic agent is thermally unstable, so when coating stretching is performed under normal conditions, volatilization or thermal decomposition occurs in the stretching and heat treatment steps. May occur, and the expected antistatic effect may not be exhibited.

In addition, when heat treatment conditions such as temperature and film retention time are relaxed, volatilization and decomposition of the antistatic agent are suppressed, and there is an antistatic effect, but the film is unsatisfactory in terms of mechanical strength and dimensional stability. Often you can only get it.

[Means for Solving the Problems]

In view of the above problems, the present inventors have conducted extensive studies, and as a result, found that a polymer having a specific structure has excellent antistatic properties and is stable in a coating and stretching step, and completed the present invention. It was

That is, the gist of the present invention is a polyester film having a coating layer obtained by a coating stretching method, wherein the coating layer contains a polymer having an ionized nitrogen element in the main chain (however, a polymer charge transfer complex is excluded). And an antistatic polyester film characterized by containing.

Hereinafter, the present invention will be described in detail.

The polyester of the polyester film in the present invention is polyethylene terephthalate in which 80 mol% or more of its constituent units are ethylene terephthalate or polyethylene naphthalate in which ethylene naphthalate is used.

The polyester film of the present invention may contain inorganic particles, organic particles, an organic lubricant, an antistatic agent, a stabilizer, a dye, a pigment, and an organic polymer as a composition, if necessary. In order to impart slipperiness to the polyester film, fine particles are contained in the film composition, and the type, size, and amount of the protrusion-forming agent are added depending on the required properties such as slipperiness and transparency of the product used. Is appropriately selected.

Examples of the polymer having an ionized nitrogen element in the main chain in the present invention include ionene polymer (Ionene polymer).
Polymer). For ionene polymers, ALAN D.WILSON and HAVARD J.PROSSER (E
d.) "DEVELOPMENTS IN IONIC POLYMERS-2" ELS
EVIER APPLIEDSCIENCE PUBLISHERS, 1986, No. 16
“IONENE POLYMERS; PREPARATI” in Chapter 4 on pages 3 to 189
ON, PROPERTIES AND APPLICATIONS ", and the following structures are shown as typical examples of ionene polymers, but the present invention is not limited thereto.

As a method for synthesizing an ionene polymer, the following reactions described in the previous document can be applied, but are not limited thereto.

Furthermore, examples of ionene polymers or derivatives thereof include JP-B-53-23377 and JP-B-54-10039.
JP-A-47-34581, JP-A-56-76451, JP-A-58-93710, JP-A-61-18750, JP-A-63
Examples thereof include compounds described in JP-A-68687, but are not limited thereto. Examples of commercially available ionene polymers are shown in Table 1 by Nippon Kasei Co., Ltd.
However, the structure is not limited to these.

The coating liquid in the present invention is preferably a polymer having an ionized nitrogen element in the main chain dissolved or dispersed in water. The medium of the coating solution is preferably water, but alcohols, cellosolves, N-methylpyrrolidone are used for improving the cohesive stability of the coating agent, the coating property of the substrate on the polyester film, and the film forming property of the coating agent. An organic solvent such as the above may be added to the coating liquid.

The coating liquid in the present invention contains a urea-based, melamine-based, or guanamine-based methylol- or alkylol-based crosslinking agent for improving the adhesion (blocking property), water resistance, solvent resistance, and mechanical strength of the coating layer. , Acrylamide-based, polyamide-based compounds, epoxy compounds, aziridine compounds, blocked polyisocyanates, silane coupling agents, titanium coupling agents, zircoaluminate coupling agents, heat, peroxides, photoreactive vinyl compounds Or a photosensitive resin may be contained. Further, as inorganic particles for improving stickiness and slipperiness, silica, silica sol, alumina, alumina sol, zirconium sol, kaolin, talc, calcium carbonate, titanium oxide, barium salt, carbon black, molybdenum sulfide, antimony oxide sol, etc. May be contained, and if necessary, a defoaming agent, a coatability improving agent, a thickener, an organic lubricant, organic polymer particles, an antioxidant, an ultraviolet absorber, a foaming agent, a dye, etc. May be contained. Further, the coating liquid of the present invention may contain a polymer other than the polymer of the present invention for improving the properties of the coating liquid or the coating layer.

As a method for applying the above-mentioned coating liquid to a polyester film, a reverse roll coater, a gravure coater, a rod coater, an air doctor coater or other coating device shown in "Coating Method" by Yuji Harazaki, Maki Shoten, issued in 1979. Polyester unstretched film coating solution using a method of sequentially or simultaneously biaxially stretching, a method of applying to a uniaxially stretched polyester film, and further stretching in the direction perpendicular to the uniaxially stretched aroma, or biaxially Apply to stretched polyester film,
Further, there is a method of stretching in the transverse and / or longitudinal direction.

The above stretching step is preferably performed at 60 to 130 ° C., and the stretching ratio is at least 4 times or more, preferably 6 to 20 times in terms of area ratio. Stretched film is 150-250
Heat treated at ℃.

Further, it is preferable to relax 0.2 to 20% in the longitudinal and transverse directions in the maximum temperature zone of the heat treatment and / or the cooling zone at the heat treatment outlet.

In particular, the coating solution is applied to a uniaxially stretched polyester film stretched 2 to 6 times by a roll stretching method at 60 to 130 ° C, and the coating solution is appropriately dried, or the polyester uniaxially stretched film is immediately dried without being dried. It is preferable to stretch the film in a direction perpendicular to the direction at a temperature of 80 to 130 ° C. by a factor of 2 to 6 and heat-treat at 150 to 250 ° C. for 1 to 600 seconds.

According to this method, the coating layer can be dried at the same time as stretching, and the thickness of the coating layer can be thinned according to the stretching ratio, so that a film suitable as a polyester film substrate can be produced at a relatively low cost. it can.

The coating liquid in the present invention may be applied to only one surface of the polyester film or may be applied to both surfaces. When coated on only one side, a coating layer other than the coating liquid of the present invention may be formed on the opposite side, if necessary, to impart other properties to the polyester film of the present invention.
In addition, in order to improve the coating property and the adhesive property of the coating agent on the film, the film may be subjected to a chemical treatment or a discharge treatment before the coating. Further, in order to improve the adhesiveness and coatability of the biaxially stretched polyester film of the present invention to the coating layer, the coating layer may be subjected to discharge treatment after forming the coating layer.

The polyester film coated with the coating solution of the present invention obtained as described above preferably has a polyester film thickness of 3 to 500 μm, and a coating layer thickness of 0.01 to 5 μm. The range is more preferably 0.02 to 1 μm. Coating layer thickness is 0.01μ
If it is less than m, it is difficult to obtain a uniform coating layer, so that coating unevenness is likely to occur in the product, and if it is more than 5 μm, the slipperiness is lowered and the film becomes difficult to handle, which is not preferable.

[Examples] Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to the following examples unless the gist thereof is exceeded.

The evaluation method in the examples was based on the method described below.

(1) Charge decay property: Using a static Honest meter (trade name) manufactured by Shishido Trading Company, at a temperature of 23 ° C. and 50% RH, apply a voltage of 10 KV to the discharge electrode located 2 cm above the sample. The film was charged, and the discharge was stopped after the charge amount was saturated. After that, the charge decay property of the sample was measured with an electrometer located 2 cm above the sample, and the half-life was used as a guide.

5 seconds or less: Very good 5 to 30 seconds: Good 30 to 600 seconds: Somewhat good 600 seconds or more: Poor (2) Surface resistivity: Concentricity of inner electrode 50mm diameter and outer electrode 70mm diameter of Yokogawa / Hewlett-Packard Company The type electrode 16008A (trade name) is installed on the sample in the atmosphere of 23 ° C and 50% RH, and the voltage of 100V is applied.
The surface resistivity of the sample was measured with 4329A (trade name), and the following judgment was made based on the resistivity value.

10 ⁹ Ω / □ or less: Very good 10 ⁹ to 10 ¹¹ Ω / □: Good 10 ¹¹ to 10 ¹³ Ω / □: Slightly good 10 ¹³ Ω / □ or more: Poor (3) Ash test 23 ℃, 50% RH atmosphere Hold the gauze under your fingertips underneath and rub the sample surface 10 times to charge the film and bring it closer to Syloid 150 (trade name), which is silica particles of Fuji Davison, and measure the distance that the particles are adsorbed to the film. The criteria were as follows.

0 to 0.5 cm: (good) 0.5 to 2 cm: (somewhat bad) 2 cm or more: (poor) In this test, when the coating film is damaged by the friction of the gauze, the antistatic effect is lost, so the coating film strength Is also evaluated.

Comparative Example 1 Polyethylene terephthalate having an intrinsic viscosity of 0.65 was added at 280 ° C to 3
It was melt extruded at a temperature of 0 ° C. and cast on a cooling drum while also using the electrostatic adhesion method to obtain an amorphous film having a thickness of 820 μm. This film is stretched 3.3 times in the machine direction at 95 ° C,
Further, it was laterally stretched 3.3 times at 110 ° C. and heat-treated at 210 ° C. to obtain a biaxially stretched polyester film having a thickness of 75 μm.

The charge decay properties, surface resistivity, and ash test results of the obtained film were poor.

Example 1 A coating solution (A) comprising 20 parts of polyvinyl alcohol having a saponification degree of 88% and a degree of polymerization of 800 (solid content, the same applies hereinafter) and 80 parts of KA1092 (trade name) which is an ionene polymer manufactured by Nippon Kasei Co., Ltd., A coating solution (B) consisting of 20 parts of the polyvinyl alcohol and 80 parts of KA1600 (trade name) and a coating solution (C) consisting of 20 parts of the polyvinyl alcohol and KA1700 (trade name) were longitudinally stretched in Comparative Example 1, respectively. After that, the film was applied before transverse stretching, and a film having a substrate polyester film thickness of 75 μm and a coating layer thickness of 0.04 μm was obtained in the same manner as in Comparative Example 1 thereafter.

The films using any of the coating liquids (A), (B), and (C) were extremely good in charge decay property and surface specific resistance, and were also good films in the ash test.

Example 2 Polyvinyl alcohol 10 having a saponification degree of 88% and a polymerization degree of 800
KA1700, an ionene polymer manufactured by Nippon Kasei Co., Ltd.
A coating solution containing 80 parts of (trade name) and 10 parts of alkylol melamine in water as a medium is applied in the same manner as in Example 1 to form a base polyester film having a thickness of 75 μm and a coating layer having a thickness of 0.03 μm. I got a film that is

The charge decay properties, surface resistivity, and ash test results of the obtained film were extremely good.

Example 3 Polyvinyl alcohol 40 having a degree of conversion of 88% and a degree of polymerization of 800
KA1600, an ionene polymer manufactured by Nippon Kasei Co., Ltd.
(Brand name) 40 parts, Alkyrol melamine 10 parts, Zircosol ZC which is a zirconium compound manufactured by Daiichi Rare Element Chemicals Co., Ltd.
A film having a thickness of the polyester film of the substrate of 75 μm and a thickness of the coating layer of 0.03 μm, which is obtained by applying a coating solution containing 10 parts of (trade name) -2 as a medium in the same manner as in Example 1. Got

The obtained film was good in charge decay property and surface specific resistance, and was also extremely good in the ash test.

Example 4 280 polyethylene terephthalate having an intrinsic viscosity of 0.62 containing 0.9% by weight of polyethylene glycol having a molecular weight of 9000
It was melt extruded at a temperature of up to 300 ° C. and cast on a cooling drum while also using the electrostatic adhesion method to obtain an amorphous film having a thickness of 182 μm. This film was stretched 3.9 times in the machine direction at 95 ℃, and the saponification degree was 88% and the polymerization degree was 80% on one side.
20 parts of polyvinyl alcohol, 40 parts of KA1700 (trade name) which is an ionene polymer manufactured by Nippon Kasei Co., Ltd., and 40 parts of alkylol melamine are applied as a water-based coating solution, and then 3.9 times in the lateral direction. The film was stretched and heat-treated at 230 ° C. to obtain a film having a base polyester film having a thickness of 12 μm and a coating layer having a thickness of 0.04 μm.

The obtained film was good in charge decay property and surface specific resistance, and the evaluation result of the ash test was also very good.

〔The invention's effect〕

As described above, the ionene polymer, which is a polymer having an ionic nitrogen element in the main chain, is excellent in thermal stability in the coating and drawing step, and the polyester film of the present invention containing the polymer in the coating layer, It has excellent antistatic properties.

The polyester film having antistatic properties of the present invention,
Not only good workability in the lamination process such as coating, vapor deposition, printing and laminating on the antistatic coating layer or on the surface not having the antistatic coating layer, but improved antistatic property of the laminated product. It is useful in many applications such as magnetic recording media, graphic arts, displays, packaging materials, building materials, information recording materials and cards.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location C08L 67:00 (72) Inventor Yoshihiko Ito 1000 Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa Daifoil stocks Central Research Laboratory (72) Inventor Shinichi Kinoshita 1000 Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa Daifoil Co., Ltd. Central Research Laboratory (56) Reference JP-A-1-232610 (JP, A)

Claims (1)

[Claims] 1. A polyester film having a coating layer obtained by a coating stretching method, wherein the coating layer contains a polymer having an ionized nitrogen element in the main chain (excluding a polymer charge transfer complex). An antistatic polyester film characterized by: